Abstract
The influence of water-cement ratio and cement content on the performance of seaweed-modified (Gracilaria Sp.) mortar was investigated in this study. The experiment was performed using seaweed-modified and unmodified mortars with different water-cement ratios. The modified mortars contained different cement percentages ranged between 21%-30%. The water-cement ratio varied from 0.33-0.6. The flexural strengths of unmodified samples responded insignificantly to the change of water-cement proportion or cement rate. Compressive and flexural strengths of the modified mortars were increased with the higher cement proportions. For higher cement portions and low water-cement proportions, the adhesion strength of the modified samples was enhanced under the wet condition. Shrinkage and water absorption of the modified samples increased with growth of cement proportion and constant water-cement ratio. The scientific application of this green technology can make the concrete environment friendly and greatly reduce the carbon-di-oxide emission as well. The commercial application of this technology can contribute to the cost reduction of the production process.
Keywords: “Seaweed Powder (Gracilaria Sp)”“Water-Cement Proportion”“Cement Portion”
Introduction
The effect of the water-cement proportion and cement percentage on the performance of the mortars is apparent (Singh, Munjal, & Thammishetti, 2015). The cement producers have reported that higher water content decreases compressive strength of concrete, but low moisture content leads to poor workability (Popovics & Ujhelyi, 2008).The effect of cement proportion and w/c proportion on the flexural strength of seaweed- modified mortars has not been studied yet. (J.-H. Lee, Cho, Choi, & Kim, 2016) reported an apparent relationship between compressive and flexural properties of concrete.
Problem Statement
In particular, flexural strength changes in a range of 5 to 8 N/mm2. This strength reduces to a greater magnitude with the increase of W/C ratios compare with compressive properties of concrete (Mohamed, 2016). The effect of cement proportion and w/c ratio on adhesion strength of the seaweed- modified composites has not been studied yet. (Yoo, Kim, Park, Park, & Kim, 2017) reported the effect of higher cement proportion and W/C ratio while the shrinkage of cement mortars was enhanced. In the present work, if all these literatures stated above are still valid when seaweed-modified mortars are used. The experiments were performed by modified and unmodified samples. Particulars of the experiments have been discussed in materials and methods subdivision. Also, the effect of Seaweed powder (Gracilaria Sp.) at a solid resin: cement proportion of 0.1 and the effect of shrinkage decreasing proxy at fixed admixture: cement proportion of 0.006 were added. The seaweed- modified mortars may be used for the renovation of concrete.
Research Questions
What is the effect of W/C ratio and cement proportion on the performance of seaweed modified mortar has not been studied till to date?
Purpose of the Study
To study the effect of W/C ratio and cement proportion on the performance of seaweed modified mortar was the main objective of this paper.
Research Methods
All the experiments were carried out with a portland cement CEM l strength class 42.5 N and a sand mixture according to MS EN 197-1. The following were also used:
Seaweed powder (Gracilaria Sp.) (Supplied by Eastern Pretech (Malaysia) Sdn Bhd), shrinkage reducing agent MAPECURE SRA 25, wetting agent (INNOVA PA 920), defoamer (BEVALOID 581B), fly ash (ST-Filler, Keller Dortmund) Micro-silica (Newreach).
The sand proportion was constantly fixed to attain hundred portions.
Design 1
Design 2
For the unmodified mortars the MS EN 197-1 standard was followed and continued with sand mix by MS; design was maintained to hundred portions with a different proportion of sand portion. The cement proportion ranged within 16–50% of mixture. Mixing of the mortars was performed according to MS EN 197-1 in a Rometa-Mixer machine. The properties of mortar workability were listed in Table
Findings
Compressive strength
Table
Flexural strength
The effect of water-cement proportion on flexural strength of extremely modified samples changes for distinct storing environments. The changes were shown in Table
Adhesion strength
The addition of mortars to film developing thermoplastics, such as seaweed powders, increased the adhesion bonding on different materials significantly. This was the principal cause for the global application of this material (S.-J. Lee, Kim, & Won, 2017). Due to the less adhesion and the weaknesses integral bonding of the unmodified sample in the thin coating on roofs, the bond strength after storing with Calcium hydroxide state could not be measured as the mortars were already damaged after core-drilling. The adhesion strength of these modified mortars after the pull-off test was approximately 0.15–0.4 N/mm2. This strength was significantly increased after the polymer modification (Table
Shrinkage
Shrinkage of the mortars depends on the water-cement proportion and the cement concentration (Piasta & Zarzycki, 2017). With the increase of the water-cement ratio, in addition to an increased cement portion of the mortar, shrinkage of the toughening sample was enhanced (Figure
Water absorption
Water enters into the pores of the mortar. Thus, a mortar sample having a lower pore size had a lower liquid absorption. The water absorption of the modified samples was decreased with a lower water-cement proportion when compared with the unmodified samples (Figure
Conclusions
The effect of water cement proportion and cement concentration on the features of polymer-modified mortars (applied for concrete repair works) had the same effect for unmodified mortars. Compressive strength was reduced with higher water cement proportion, and the cement concentration was of negligible effect. Shrinkage and water absorption were enhanced with the higher water cement proportion and cement level. The flexural strength of unmodified samples at water-cement ratios of 0.41–0.61 was almost independent of water cement proportion and cement level. The flexural strength of the polymer-modified samples was increased than the unmodified samples. The flexural strength of the modified samples at the higher water-cement proportion was reduced slightly after 28 and 90 days storing in an ideal climate. On the other hand, after underwater storage of the modified samples, there was a considerable decrease in the flexural strength with higher water-cement proportions. The effect of the cement concentration on the flexural strength of the mortars was not of first order. The adhesion strength of the polymer-modified sample was much greater in comparison to that of the unmodified sample; there was only a minor influence of the water-cement proportion, and an increasing cement concentration increased the adhesion. The outcome of this work fits exactly into the concept of the composite compound, as the polymer-modified samples showed. Both binders acted in collaboration: cement being the inorganic binder was accountable for mechanical solidity regarding compressive strength and the seaweed powder being the organic one was performing as a reinforcement and was responsible for inner tensile strength and outer adhesion-bond strength. As both binders were working simultaneously, the new polymer-modified mortars may reach to the industrial revolution that unmodified mortars cannot.
Acknowledgments
The authors are thankful to the Faculty of Engineering Technology at the University of Malaysia, Pahang for allowing continuous access to their laboratory services. The present study was made possible by the RDU-1601316 grant.
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About this article
Publication Date
17 May 2019
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978-1-80296-061-7
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Future Academy
Volume
62
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1st Edition
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Business, innovation, sustainability, environment, green business, environmental issues
Cite this article as:
Ab. Wahid, Z., & Siddique*, N. I. (2019). Effect Of Water-Cement Ratio On Performance Of Seaweed-Modified Mortars. In M. Imran Qureshi (Ed.), Technology & Society: A Multidisciplinary Pathway for Sustainable Development, vol 62. European Proceedings of Social and Behavioural Sciences (pp. 212-221). Future Academy. https://doi.org/10.15405/epsbs.2019.05.02.20